whenever i go near my bearded dragon his beard turns black?

 
Whenever i go near my bearded dragon his beard turns black?
starting today i brought my bearded dragon out and i watched tv and then he pooped on me and i cleaned it up then his beard turned black and i put him back in his cage and whenever i look at him and he can see me his beard starts to turn black again (i already kno that when his beard is black he is stressed out or mad) but what did i do to him?
its a sign of aggression. his cage is the only world he knows and he is just trying to protect it. he doesnt understand. i have a rabbit just like that, she tries to bite and claw when i come near. try feeding him from your hand but hold a bowl so you dont get bit. i have tried this with my rabbit and she is gradually getting better. my theory is this, when they think you=food, then they think you=good